text: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CONTENT_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_PLACEHOLDER_H_
  #define CONTENT_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_PLACEHOLDER_H_
  #pragma once
  
  #include "base/process.h"
  #include "ipc/ipc_channel_handle.h"
  #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
  #include "third_party/WebKit/Source/WebKit/chromium/public/WebPluginParams.h"
  #include "ui/gfx/size.h"
  #include "webkit/plugins/webview_plugin.h"
  
  namespace content {
  class RenderView;
  }
  
  namespace WebKit {
  class WebPlugin;
  }
  
  // A browser plugin is a plugin container that hosts an out-of-process "guest"
  // RenderView. Loading up a new process, creating a new RenderView, navigating
  // to a given URL, and establishing a guest-to-host channel can take hundreds
  // of milliseconds. Furthermore, a RenderView's associated browser-side
  // WebContents, RenderViewHost, and SiteInstance must be created and accessed on
  // the UI thread of the browser process.
  //
  // To avoid blocking the host RenderView and to avoid introducing the potential
  // for deadlock, the BrowserPluginPlaceholder takes place of the guest
  // RenderView until the guest has established a connection with its host
  // RenderView. This permits loading the guest to happen asynchronously, while
  // the host RenderView is permitted to continue to receive and process events.
  class BrowserPluginPlaceholder: public webkit::WebViewPlugin::Delegate {
   public:
    // Creates a new WebViewPlugin with a BrowserPluginPlaceholder as a delegate.
    static webkit::WebViewPlugin* Create(
        content::RenderView* render_view,
        WebKit::WebFrame* frame,
        const WebKit::WebPluginParams& params);
  
    static BrowserPluginPlaceholder* FromID(int id);
  
    void RegisterPlaceholder(int id, BrowserPluginPlaceholder* placeholder);
    void UnregisterPlaceholder(int id);
  
    int GetID() { return id_; }
  
    webkit::WebViewPlugin* plugin() { return plugin_; }
  
    const WebKit::WebPluginParams& plugin_params() const;
  
    void GuestReady(base::ProcessHandle process_handle,
                    const IPC::ChannelHandle& channel_handle);
  
    content::RenderView* render_view() { return render_view_; }
  
   private:
    BrowserPluginPlaceholder(content::RenderView* render_view,
                             WebKit::WebFrame* frame,
                             const WebKit::WebPluginParams& params,
                             const std::string& html_data);
    virtual ~BrowserPluginPlaceholder();
  
    // Grabs the width, height, and source URL of the browser plugin
    // from the element's attributes. If not found, it uses the defaults
    // specified here as parameters.
    void GetPluginParameters(int default_width, int default_height,
                             const std::string& default_src);
    // Replace this placeholder with the real browser plugin.
    void LoadGuest(WebKit::WebPlugin* new_plugin);
  
    virtual void BindWebFrame(WebKit::WebFrame* frame) OVERRIDE { }
    virtual void WillDestroyPlugin() OVERRIDE;
    virtual void ShowContextMenu(const WebKit::WebMouseEvent&) OVERRIDE { }
  
    content::RenderView* render_view_;
    WebKit::WebPluginParams plugin_params_;
    webkit::WebViewPlugin* plugin_;
    int id_;
    gfx::Size size_;
    std::string src_;
  
    DISALLOW_COPY_AND_ASSIGN(BrowserPluginPlaceholder);
  };
  
  #endif  // CONTNET_RENDERER_BROWSER_PLUGIN_BROWSER_PLUGIN_PLACEHOLDER_H_
  